The central focus of the Cytogenetics Shared Resource (CSR) is to provide cytogenetic and molecular cytogenetic analysis of human and animal model research samples. These samples may be in the form of cultured cells, fresh or frozen tissue, paraffin-embedded sections, or tissue microarrays (TMAs). Specific cell types include tumor cell lines, xenograft cells, hybrid cells from chimeric animal models, neural stem cells, and mouse embryonic fibroblasts, among others. The CSR provides specialized services including cell culture, routine cytogenetic analysis, chromosome breakage analysis, interphase and metaphase Fluorescence in situ Hybridization (FISH), Spectral Karyotyping (SKY) analysis of human and mouse metaphases, and homebrew FISH Probe Production. This last service provides novel FISH probes that are specific to investigators needs and are usually not commercially available. These probes are then used for FISH analysis studies. The CSR is expanding this service beyond homebrew enumeration FISH probes by creating custom translocation/fusion probes, break-apart probes, and multi-color FISH probes to ultimately assist in developing strategic probes that become clinical diagnostic and prognostic markers of disease. Other services provided by the CSR to meet the needs of investigators include utilization of the CSR laboratory for slide processing and fluorescent microscope and imaging system use. Briefly, applications of CSR services include: to characterize the clonality of tumor specimens; to determine the origin of a specific tumor culture (i.e., mouse vs. human), to aid in the identification of genetic regions important for the development of specific malignancies, and to map the location of DMA sequences, genes, or transgene insertions. With the recognition that cancer is a genetic disease, many cancer researchers, including scientists in the Mayo Clinic Cancer Center (MCCC), require access to CSR services. This Shared Resource is utilized by 9 of the 12 Cancer Center Programs. Approximately 66% of CSR users are CCSG members and represent 92% of the overall utilization.